Do you turn off your refrigerator at night?

This is what some of my friends are doing in order to save power. Does this work? They say it is enough to turn it on the whole day, the coldness it creates in the day will keep the food fresh even when you unplug or turn off your refrigerator. This way, they save money as power is saved. Is this true? I would like to try it because I want to save on my power consumption. I do not want to be paying much on power consumption. Please share your observations.